CAJ | 학술논문

在应用瞬时单位线(IUH)进行流域汇流模拟时,需要先率定其2个参数:线性水库的个数n及调蓄系数K.研究表明,用传统的矩法率定得到的IUH,对地面径流的模拟精度较差,需要对参数进行更新.此前袁作新给出了一个用于参数更新的递归公式.本文推导了一个新的递归公式,并与袁作新公式的应用效果进行了对比.新递归方程的推导原理是针对地面径流过程线的2个特征值:洪峰流量和峰现时间,按模拟值与观测值之间的比来调整参数n和K,以使调整后得到的地面径流尽量接近观测值,调整的目标函数选取确定性系数(DC)和误差的均方值(MSE).将新递归公式和袁作新公式应用于2个案例.结果表明,新递归公式在提高地面径流模拟精度上要优于袁作新公式,对于案例1,新递归公式能提高模拟精度,而袁作新公式则不能;时于案例2,新递归公式提高模拟精度的幅度要高于袁作新公式,DC值提高了1.1%,MSE值降低了14.2%.分析原因认为较大的参数调整幅度可能跨越最优点,而新递归公式对参数的调整幅度小于袁作新公式,从而使其能够找到最优点.应用本文的递归公式时,不宜调整次数过多,否则会降低地面径流模拟精度,对2个案例的最优调整次数均为2次,产生此现象的原因是增加调整次数虽然可以提高时洪峰流量和峰现时间的模拟精度,但不一定能提高对整个地面径流过程的模拟精度.
재응용순시단위선(IUH)진행류역회류모의시,수요선솔정기2개삼수:선성수고적개수n급조축계수K.연구표명,용전통적구법솔정득도적IUH,대지면경류적모의정도교차,수요대삼수진행경신.차전원작신급출료일개용우삼수경신적체귀공식.본문추도료일개신적체귀공식,병여원작신공식적응용효과진행료대비.신체귀방정적추도원리시침대지면경류과정선적2개특정치:홍봉류량화봉현시간,안모의치여관측치지간적비래조정삼수n화K,이사조정후득도적지면경류진량접근관측치,조정적목표함수선취학정성계수(DC)화오차적균방치(MSE).장신체귀공식화원작신공식응용우2개안례.결과표명,신체귀공식재제고지면경류모의정도상요우우원작신공식,대우안례1,신체귀공식능제고모의정도,이원작신공식칙불능;시우안례2,신체귀공식제고모의정도적폭도요고우원작신공식,DC치제고료1.1%,MSE치강저료14.2%.분석원인인위교대적삼수조정폭도가능과월최우점,이신체귀공식대삼수적조정폭도소우원작신공식,종이사기능구조도최우점.응용본문적체귀공식시,불의조정차수과다,부칙회강저지면경류모의정도,대2개안례적최우조정차수균위2차,산생차현상적원인시증가조정차수수연가이제고시홍봉류량화봉현시간적모의정도,단불일정능제고대정개지면경류과정적모의정도.
Instantaneous unit hydrograph is the outflow from the instantaneous application of unit net rainfall over the catchment.The IUH is widely used for surface runoff simulation by using net rainfall as input.The IUH consists of 2 parameters,n and K,the determination of which is normally made by using the moment method.It was found in previous researches that the calculated surface runoffs based on the parameters from the moment method did not fit the observed ones well,an updating of the parameters is necessary.Therefore,the aim of this study is to firstly derive a recursive equation for parameter updating of the IUHs,and secondly investigate the appropriate number of updating times for applying the derived equation.As the most important characteristics of the surface runoff hydrographs are the peak discharge(Qp)and the time of the rising limb(of the surface hydrograph)to reach the peak(tp),the recursive equation was deduced by adjusting the calculated Qp and tp repeatedly so as to try to be equal to the observed Qp and tp When applying the deduced recursive equation,it was found that the number of updating times should be appropriate,for too many number of updating times will deteriorate the performance of the IUH for simulating the surface runoffs.2 flooding events were used for testing the recursive equation derived in this study.The results show that the appropriate number of updating times for both 2 flooding events are 2.After that number of updating times,the deterministic coefficient(DC)and mean squares error(MSE)between the calculated and observed surface runoffs will no longer be improved.The reason of the existence of this appropriate updating number is that,the updating targets:the Qp and tp,are actually indicating partial characterization of the surface runoffs.A precise convergence of the calculated Qp and tp to observed ones does not necessarily guarantee a monotonic improvement of the simulation for the overall course of the surface runoffs,which is indicated by the DC and the MSE.This indicates a lack of parameterization of the IUH,an increase of the number of parameters of the IUH may improve its performance on surface runoff simulation.